Elmer/Ice News

Inverse method for sliding coefficients at Vestfonna ice cap

Comparison between modelled (left) and observed (right) surface velocities

In a recent publication in The Cryosphere Schäfer et al. use a Robin inverse method  to infer the basal  friction from the surface velocities observed in 1995 for the Vestfonna  ice cap on Svalbard. The results demonstrate that especially the ice caps on Nordaustlandet,  with their mixture of static central parts and fast moving outlet glaciers, demand the correct spatial distribution of sliding coefficients and that  - in lack of  a complete understanding of the physics taking place at the bedrock - inverse models for the time being are the only means to deliver that spatial distribution. Further investigations of  comparison of sliding  coefficients  obtained  for datasets taken at different times shall shed further light on the nature of the sliding underneath Vestfonna ice cap.

Glacier Volume/Area relation

image SurenGRLIn Adhikari and Marshall (2012, Geophys. Res. Lett.), the 3D high-order Elmer/Ice model is used to investigate how different topographic and climatic settings, flow dynamics, and the degree of disequilibrium with climate systematically affect the glacier volume-area relation. Authors recommend more accurate scaling relations through characterization of glacier-specific morphology. This motivates a revision of global glacier volume estimates, of some urgency in sea level rise assessments.

Elmer/Ice and Ice2sea

GrIS FabienIn a paper under revision for The Cryosphere (paper under discussion at http://www.the-cryosphere-discuss.net/6/2789/2012/tcd-6-2789-2012.html), we investigate with Elmer/Ice how current ice loss of the Greenland Ice Sheet may endure over the next century. This relies on three essential developments: the complete solution of the full system of equations governing ice deformation; an unstructured mesh to usefully resolve outlet glaciers and the use of inverse methods to better constrain poorly known parameters using observations. We show that the modelled ice discharge is in good agreement with observations on the continental scale and for individual outlets. By conducting perturbation experiments, we find that increasing ablation tends to reduce outflow and on its own has a stabilising effect, if destabilisation processes maintain themselves over time, current increases in the rate of ice loss are likely to continue. This work was performed using HPC resources from GENCI-CINES and from the Grenoble University High Performance Computing centre. This work is a contribution to the ice2sea project.

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